Hello,
We already have this thread .pls refer
Difference Between SharePoint Site and ASP.NET Site[
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Anyways a thought about this vauge question! ASP.net vs Sharepoint !to make it simple.In a generic way in my own word
Sharepoint is a CMS or ERP system and it acts as server by itself.
Asp.net used to create web pages and web technologies and is an integral part of Microsoft’s .NET framework .
Both use .net Framework as the base and using Visual Studio Asp.net solution can be integrated to WSS.
Hope it helps.All the Best:)